Let's turn to the latest adventure for prince harry. He was locked in a special d-3 chamber overnight, to support a cause for wounded soldiers. He's fought in afghanistan. Commanded helicopters. Now, prince harry is taking on a new challenge, the south pole. How was it, harry? Cold. Reporter: This morning, the prince battled sub zero temperatures with his team inside a franing chamber. In the training exercise, prince harry could be seen emptying his tent, using a hammer. The wind blew and the temperatures dipped as low as 49 below zero. The real journey alongside wounded soldiers to the antarctic in november, the goal, to raise funds for walking with the wounded, a charity that provides rehabilitation services for military veterans. We've just shown people what is possible. Reporter: The 16-day race against the south pole will pit the prince's u.K. Team against teams from the u.S., Canada and australia, and will feature at least one other big name, alexander scarsgar, the "true blood" actor, will captain the u.S. Team. Perhaps we'll come to an arrangement. Reporter: The prince will turn 29 over the weekend, is no stranger to the cold. Is it okay if I call you prince harry? Can I call you bob? Reporter: I caught up with the prince on his way to the north pole. Part of another walking with the wounded trek. This is what it's like to spend a night in the tent at minus 25. Is that all it was? Minus 25. It was a lot colder than that in there. Reporter: Joking aside, the prince's goal then and now remains the same. Helping veterans. For "good morning america," bob woodruff, abc news, new york.

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